Arrangement of two or more anodes for rectifiers provided with control electrodes



M DEMONTVIGNIER PROVIDED WITH CONTROL ELECTRODES Filed Dec. 5, 1932 a E2 M a 0 5 w Q2. 6 5% 4 .1 fi v (IT/F M 7.

wt 1 w 3 ARRANGEMENT ,OF TWO OR MORE ANODES FOR RECTIFIERS Dec. 20,1938.

Patented Dec. 20, 1938 UNITED STATES PATENT QFFEE ARRANGEDIENT OF TWO ORMORE AN ODES FOR RECTIFKERS PROVIDED WITH CON- TROL ELECTRODESApplication December 3, 1932, Serial No. 645,633 In France December 23,1931 7 Claims.

The parallel operation of two or more anodes for arc rectifiers such asmercury vapour rectifiers in which the anodes may be in the samecontainer or separate containers, ofiers certain difficulties on accountof the negative resistance of the are. It is already known that thisparallel operation may be effected in various ways: for exam le, aninductance may be provided for each anode which, by its inductivepotential drop, will compensate the negative resistance of the arc; itis also possible to couple the dillerent anode circuits magnetically insuch a way that any anode the ignition of which is retarded, receives aninductive electromotive force in consequence of the ignition of thepreceding anodes,

which will cause it to ignite. As wil be readily appreciated, a couplingof this kind likewise enables the differences in the drop of potentialin the arc to be compensated. In the case in which the anodes requiredto operate in parallel are provided with one or more control internalelectrodes or external electrodes in their vicinity, the purpose ofwhich is either to eliminate the residual ionization which causesback-firing or to control the moment of ignition, these arrangements maybe employed; it has been proposed merely to connect the controlelectrodes in parallel and to the common voltage supply, either directlyor through resistances. This method is accompanied by a seriousdrawback: actually, when a control electrode has effected the ignitionof a single anode, its voltage drops immediately at the same time asthat of the other electrodes; consequently, the ignition of the otherelectrodes is rendered more difficult and the magnetic coupling arranement between the anodes must be strengthened in such a way as to givethe necessary impulse to the other anodes.

The object of the present invention is to provide an arrangement whichin the case of the parallel operation of two or more anodes providedwith grids enables a magnetic coupling system to be employed between theanode circuits, which is reduced to the dimensions necessary forcompensating the differences of potential drop in the arc, the controlelectrode circuits being coupled magnetically to one another and to theanode circuits in such a way that the control electrode for an anode theignition of which is delayed, will receive a positive voltage impulseowing to the ignition of the other anodes, which will effect theignition of the retarded anode.

The following description which is given by way of example withreference: to the accompanying drawing and is in no way limiting, willenable the principle of the invention and the methods of carrying itinto practice to be better understood.

Fig. 1 shows the arrangement suitable for the parallel operation of twoanodes provided with inductance coils and grids.

Fig. 2 shows the corresponding arrangement for three anodes.

Fig. 3 shows the arrangement which may be employed in the case of theparallel operation of two anodes supplied by two windings in phase withone another on the same transformer.

Fig. 4 shows an arrangement combining the magnetic coupling between twoanodes and their control grids in the same magnetic circuit.

Finally, Fig. 5 shows the corresponding arrangement for threeelectrodes.

Referring to Fig. l the common busbar I, connected to a terminal of thesecondary of the supply transformer, feeds the two anodes 2 and 3through inductances i and 5. Between the anodes 2 and 3 the primary of asmall singlephase transformer is connected; the secondary, which has avery much greater number of turns than the primary is provided with acentre tap i connected to one of the terminals of the common supply 8for controlling the grids, the ot er terminal of the same, which isshown, free in the figure, being connected to a suitable point in thesystem. The two ends of the secondary for the grid transformer areconnected respectively to the grids 9 and il the direction of couplingbeing that shown in the figure, assuming the primary and secondary ofthe grid transformer to be wound in the same direction. With this stateof affairs let it be assumed for example that under the influence of thesupply 8 the grid 5 controls the first ignition of the anode 2; underthese conditions this anode will undergo a sudden drop of potential,equal to the difierence between the ignition voltage and the drop ofpotential in the arc (the ignition voltage being moreover determined bythe selection of the moment of ignition caused the supply 8). As thevoltage of the anode 3 does not undergo any change, a difference ofvoltage will appear suddenly between the terminals of the primary t.This difference of voltage will reappear, multiplied by the transmissionratio, between the terminal l and the grid iii, the latter beingsuddenly rendered positive. As the voltage of the anode 3 will then begreater than that of the anode 2 (owing to the inductive drop in theinductance Q) the anode 3 will be ignited. In other words, the retardingof the ignition of one anode produces a sudden positive potentialimpulse upon its grid. This impulse may be made as strong as desired byincreasing the transformation ratio of the grid transformer, the latterbeing moreover very small owing to the low value of the grid currents.Under these conditions the anodes will ignite substantially at the sametime (actually, experience has shown that the retardation is verydifficult to determine), and the anode inductances are only required tocompensate the differences of the potential drop in the ignited arc.

This system may conveniently be applied generally to the paralleloperation of three anodes provided with inductances: for example threegrid transformers may be employed arranged in a manner similar to thatof Fig. 1, between each of three anode couplings associated in pairs,the three centre points of the three secondaries being connected to oneanother and to the common supply for the grids, and each of these latterbeing connected to two secondary terminals of two grid transformers. Itwill then be readily appreciated that any anode which ignitesprematurely will apply to the grids of the two others a sudden voltageimpulse which effect their ignition. Itis moreover possible to eliminateone of the three transformers without any inconvenience resulting.Further, as shown in Fig. 2, it is possible to combine in one magneticcircuit having three cores the elements for the grid transformerrequired for the parallel operation of three anodes provided withinductances. Referring to Fig. 2, the common busbar feeds the threeanodes l2, l3 and I4 through inductances |5, I 6 and I1. On the otherhand three coils I9, 20 and 2| connected in star are placed in amagnetic circuit l8 having three cores, the free ends of the coils beingconnected to the terminals of these three anodes. In the same circuitthere are also three coils 22, 23 and 24 likewise coupled in star, theneutral point being connected to one of the terminals of the controlsupply 25 for the grids whilst the other terminal is connected to asuitable point in the system. The free ends of the coils 22, 23 and 24are connected respectively to grids 26, 21 and 28. Let it now be assumedthat under the influence of the supply 25, the anode l2 ignites firstfor example: a sudden drop it of its potential will result with respectto that of the anodes I3 and 4. It will readily be seen that this suddendrop of potential will take the form of the sudden appearance in thecoils I9, 20 and 2| of the voltages 2a 2 Y 3 and respectively, thesevoltages being reckoned positively from the neutral point. Thesevoltages will obviously reappear in the secondary, multiplied by thetransformation ratio. Consequently the grids 21 and 28 corresponding tothe anodes l3 and 4 will each receive a positive voltage impulse causingignition. Similarly, if two anodes ignite in advance, the grid of thethird will receive an impulse causing ignition. These arrangements maybe extended without difficulty to any number of anodes provided withinductances either when employing n or n1 single-phase grid transformersor a single transformer with 12 cores.

Similarly, instead of employing independent inductances in the anodecircuits, it is possible to employ magnetically coupled inductances orindependent windings on the supply transformer, these windings givingvoltages in the phase with one another and being provided with amagnetic coupling producing the inductance for the coupled anodes withinthe transformer.

Referring to Fig. 3, a single-phase grid transformer is shown forexample which is employed to produce the simultaneous ignition of twoanodes, all these members having the same references as in Fig. 1, butthe anodes are supplied by two independent windings 29 and 30 coupledtogether in the magnetic circuit of the supply transformer.

Finally, in order to ensure the parallel operation and simultaneousignition of two or more anodes for restifiers supplied with controlelectrodes, it is possible to combine in the same magnetic circuit thewindings traversed by the anode currents and the windings employed foroperating the control electrodes. This is shown in Figures 4 and 5.

Referring to Fig. 4, in a single-phase magnetic circuit 3|, two windings32 and 33 inserted in the circuits of the two anodes 34 and 35 so thattheir ampere turns are in opposition are shown. On the other hand thecontrol voltage supply 36 feeds the grids 31 and 38 through fine wirewindings 39 and 40 which are likewise in opposition in the magneticcircuit. The operation is as follows. If under the influence of thesupply 36, the anode 34 ignites first, a sudden decrease of potentialwill be produced between the terminal 4| of the supply transformersecondary and the anode 34. On the other hand, owing to the inductionthere will be a sudden increase of potential between the anode 35 andterminal 4| on the one hand, and on the other hand at the grid 38 in asimilar manner to that described above. These two increases of voltagewill cause the immediate ignition of the anode 35. It will be readilyunderstood that when the two anodes are ignited, the two windings 32 and33 compensate the differences of potential drop in the arc, theout-ofbalance current produced by a given difference of the twopotential drops being as much less as the increase of the inductance inthe windings.

The interesting feature of this arrangement is found in the fact thatthe heavy wire winding only has to compensate the difierences ofpotential drop in the arc and may be reduced to a minimum, thedifferences of ignition voltage being compensated by the fine wirewinding.

Referring to Fig. 5, the application of an arrangement similar to theparallel operation of three anodes is shown; the terminal 42 for thesecondary of the supply transformer is connected to three anodes 49, 50and 5| through three heavy wire windings 43, 44 and 45 placed in themagnetic circuit with three cores 56. In this same circuit three finewire windings are located which are coupled in star, the common pointbeing connected to the control voltage supply 55 and the free-ends beingconnected to grids 52, 53 and 54. The operation is analogous to that ofthe preceding arrangement, the fine wire windings producing thesimultaneous ignition of the three anodes and the heavy wire windingscompensating the differences of potential drop in the arc. Thiscompensation is only perfect when the reluctances of the magneticcircuits corresponding to the three cores are equal, or when the numbersof turns are selected in inverse relation to the reluctances.

In order to obtain parallel operation with three anodes it is alsopossible to associate three systems identical to that shown in Fig. 4,in such a way as to ensure the parallel operation of three pairs ofanodes combined in pairs.

These systems may also be extended to any number of anodes.

It has been assumed in what has been said above that the controlelectrodes took the form of grids. The systems described may be appliedwithout modification to a method of control with external electrodes.Similarly it is possible to insert in the control electrode circuitsresistances or impedances of any kind which are located above or belowthe arrangements described.

I claim:

1. In a rectifying system, anodes connected in parallel with the samephase of a supply transformer, an inductance in series with each of saidanodes, a control electrode for each of said anodes, a winding in serieswith each control electrode, and a means magnetically coupling each ofsaid control electrode windings and with all of said anode inductances.

2. In an electric translating circuit, a plurality of grid controlledvapor electric valves connected in parallel, a grid circuit for each ofsaid valves, means for exciting said grid circuits normally to rendersaid valves conductive simultaneously, a reactance device comprising amulti-legged core member and an inductive winding mounted on each leg ofsaid core, one of said windings being connected in the anode-cathodecircuit of each of said valves, and an auxiliary inductive windingcoupled to each of said first mentioned windings and connected incircuit with the grid of its corresponding valve, said, auxiliarywindings being effective upon the initiation of current in any of saidvalves to impress positive impulses on the grids of the non-conductivevalves.

3. In an electric translating system, the combination with a source ofelectric current, electric valve means comprising a plurality of anodesand a plurality of control electrodes severally associated with saidanodes, and means comprising a first plurality of windings severallyconnecting said anodes with said source of current, of means comprisinga second plurality of windings severally connected with said controlelectrodes and operable to excite the latter in such sense as tocontinually render the said anodes simultaneously conductive for theflow of current from said source by way of the said first plurality ofwindings, and means inductively coupling each winding of the said firstplurality thereof with all of the said second plurality of windings tothereby additionally excite said control electrodes upon the occurrenceof the initiation of said flow of current through any one of saidanodes.

4. In an electric translating system, the combination with a source ofelectric current, electric valve means comprising a plurality of anodesand a plurality of control electrodes severally associated with saidanodes, and means comprising a first plurality of windings severallyconnecting said anodes with said source of current,

of means comprising a second plurality of windings severally connectedwith said control electrodes and operable to excite the latter in suchsense as to continually render said anodes simultaneously conductive forthe flow of current from said source by way of the said first pluralityof windings, and means comprising a member of paramagnetic materialinductively coupling each winding of the said first plurality of windswith all of the said second plurality of windings to therebyadditionally excite said control electrodes upon the occurrence of theinitiation of said flow of current through any one of said anodes.

5. In an electric translating system, the combination with a source ofelectric current, electric valve means comprising a plurality of anodesand a plurality of control electrodes severally associated with saidanodes, and a plurality of inductors severally connecting said anodeswith said source of current, of means for exciting said controlelectrodes in such sense as to continually render said anodessimultaneously conductive for the flow of current from said source byway of said inductors, the last said means comprising a transformerhaving a primary winding connected across said anodes and a secondarywinding having a plurality of portions severally connected with saidcontrol electrodes and operable to additionally excite said controlelectrodes upon the intiation of said flow of current through any one ofsaid anodes.

6. In an electric translating system, the combination with a source ofelectric current, electric valve means comprising a plurality of anodesand a plurality of control electrodes severally associated with saidanodes, and a plurality of inductors severally connecting said anodeswith said source of current, of means for exciting said controlelectrodes in such sense as to continually render said anodessimultaneously conductive for the flow of current from said source byway of said inductors, the last said means comprising a transformerhaving a plurality of primary windings severally connected with saidanodes and a plurality of secondary windings severally connected withsaid control electrodes and severally inductively linked with all ofsaid primary windings to thereby additionally excite the said controlelectrodes upon the initiation of said flow of current through any oneof said anodes.

7. In an electric translating system, the combination with electricvalve means comprising a plurality of anodes and a plurality of controlelectrodes severally associated with said anodes, of means comprising aplurality of winding portions severally connected with said controlelectrodes for exciting the latter in such sense as to render the saidanodes simultaneously conductive for the flow of current, and means foradditionally exciting said control electrodes upon the occurrence of theinitiation of the flow of current through any one of said anodescomprising a winding having connection with at least two of said anodes,and a member of paramagnetic material inductively coupling the saidwinding with said plurality of winding portions.

MARCEL DEMONTVIGNIER.

